-- The Internet Protocol, or IP,
is part of the Transmission Control Protocol/Internet Protocol
(TCP/IP) protocol suite. IP is a routing protocol that determines
the best route or path for information to travel between stations
(PC workstations, file servers, or routers). Setting up and understanding
IP routing can be easy for small, less-complex networks or complicated
for large, dissimilar networks. The key to understanding IP routing
is to understand its most complex and flexible component--IP addressing.
IP addressing -- IP
addressing is a way to identify stations or hosts on a network.
An IP address is a unique 32-bit number that uses a format of
4 bytes, (four
with each byte separated by a decimal point (called dotted decimal
notation). Each byte can be a number from 0 to 255. For example,
188.8.131.52 is a valid IP address. By having unique addresses
on a network, you can identify individual stations (also called
hosts or nodes) on the single network.
An IP address
consists of two parts - one part identifies the network, and
one part identifies the host (or node). Nodes define connected
devices on a network, network users, and PCs.
assign IP addresses inside private companies using arbitrary
addresses. But if you want to connect to the internet, you must
use registered IP addresses that conform to an international
standard. IP addresses are assigned by the InterNIC registration
service. IP addresses are implemented in the network by software;
they are not assigned to equipment at the factory as are Ethernet
and token ring adapter addresses.
There are five
types of IP addresses. Three are associated with networks --
Class A, B, and C. The illustration above shows the differences
in byte assignments for networks and hosts between the three
address classes. Class B and Class C addresses have fewer host
ID bytes and more network bytes than Class A. The more network
addresses, the fewer hosts or nodes. Class A networks have more
addresses for a single network than Class B or C.
A addresses are for networks that have a large number of hosts,
up to a maximum of 16, 777, 216 on a single IP network. The
first octet (that is the first byte, or the first segment
before a decimal) is between 1 and 126. (127 is reserved for
loopback and is used for internal testing on the local machine.)
B addresses are for medium-sized networks. The first octet
is between 128 and 191.
- Class C addresses
are for small networks, with up to 255 hosts. The first octet
is between 192 and 223.
- Class D addresses
are reserved for multicasting and the first octet is between
224 and 239.
E addresses (240 to 255) are reserved and should not be used.